The present invention relates to a backup technique in a computer system.
Recently, as data amount increases, a computer system used in a company or the like becomes larger in its scale. However, when an additional storage apparatus is provided, backup work becomes complex and expensive. For example, a backup apparatus should be provided for each computer, to perform backup processing. Thus, it is considered for example that host computers (hereinafter, simply referred to as hosts), a storage system and a tape device are connected to a network called SAN (Storage Area Network), and data of all the storage apparatuses are backed up in a batch by a server (hereinafter, referred to as a backup server) used exclusively for backup processing. For example, Japanese Patent Application Laid-Open No. 2002-7304 discloses a method in which data in a storage apparatus used by another server connected to a SAN are backed up by a backup server into a tape device and a method in which a plurality of hosts shares the tape device. As a result, backup can be performed without loading a server that is executing ordinary service, and construction costs of a computer system can be reduced.
Further, there is widely used an apparatus called NAS (Network Attached Storage) that is connected to a LAN (Local Area Network) interconnecting a plurality of hosts. NAS is an apparatus that serves hosts with data access using a network file access protocol such as NFS (Network File System), CIFS (Common Internet File System) or the like, and comprises a storage part for storing files and a NAS head part (hereinafter, referred to as a file server) for processing a file access request from a host. NAS is easy in data sharing by a plurality of hosts and in setting operation, and accordingly, even a medium or large scale site comes to employ a NAS, and there appears some apparatus having a plurality of file servers to increase performance and reliability.
In many cases, each maker of a NAS for business use employs an original OS and an original file system for the sake of high performance and high reliability, and thus it is very difficult to install backup software that sells on the market and that can be used in an ordinary host. As a result, generally, a method using NDMP (Network Data Management Protocol) is employed to perform backup. NDMP is a protocol for backup processing between a NAS apparatus and an external apparatus having backup software. In the case of an NDMP-capable NAS apparatus, backup operation and restoring operation can be performed from an apparatus that has backup software adapted for NDMP. In other words, one apparatus having backup software can perform backup operation for NASs of various makers. Thus, NDMP is a de facto standard. O'Reilly Japan, Inc., “SAN & NAS storage network management”, pp. 193–221 discloses some NAS backup methods using NDMP.